1. Field of the Invention
This invention relates to an anti-theft locking device adapted for mounting on the steering column of an automotive vehicle.
2. Description of the Related Art
It is well known in the patented prior art to provide a vehicle steering assembly including a steering column that is connected at one end with the vehicle steering wheel, the other end of the steering column being connected with the front steering wheels of the vehicle via steering box means.
Anti-theft locking devices have been proposed that do not include any torque limiting means, such as, for example, a locking system including a locking bolt that engages a component that is integral with the steering column. These locking systems possess the drawback of possibly being destroyed or degraded by the rupture or bending of the locking bolt, thereby producing a dangerous driving condition accompanied by untimely locking of the steering shaft as a consequence of the deformed or disintegrated parts.
There have also been proposed locking devices that include torque limiting means which permit the steering shaft to rotate upon the application of a predetermined torque force, thereby to prevent the destruction of the components of the device and to keep the parts from interfering with the normal driving of the vehicle. In this type of device, the use of a split sleeve has been proposed which is equipped with an elastic element which provides a frictional force that must be overcome to effect rotation of the steering shaft.
Also known are locking systems having a pair of elements equipped with radial teeth which are associated with an resilient element for the disengagement of the steering shaft upon the development of a certain rotational torque. It has also been proposed to use assemblies having a sleeve whose circular inside face encloses the steering shaft according to a value that allows said steering shaft to rotate when a predetermined determined torque force is exceeded.
Finally, assemblies are known having a tubular sleeve whose outer face is equipped with hollow axial deformations that are intended to receive the bolt of the locking device. Outer hollow axial deformations are provided on the inside face that are then tightened upon the steering shaft, which can thus rotate, starting as of a certain torque applied upon the steering wheel.
The different applications of this type of torque limiting system possess the drawback of employing either complex assemblies that require numerous components, thereby increasing the cost and the size of the locking system, or assemblies having a single sleeve whose torque is difficult to control or whose internal structure is tied to the external structure.
The present invention was developed to provide a rotational torque-responsive locking device on a vehicle steering column that avoids the above and other drawbacks of the prior art, and which provides a simple and rather small device that produces a precisely designed and reliable disengagement torque and that allows great flexibility of adaptation between the steering shaft and the engagement of the locking arm of a locking device.